fryedaddy

Can anyone give me some info. I have a 96 pretty much stock truck 170K miles. I'm experiencing low voltages, cycling voltage. I had it checked at autozone last week they told me the batteries, alternator looked good.
I have since went to O'reily's and they told me I had on bad battery, a bad diode in the alternator. I installed 2 new batteries and alternator, belt and 120 AMP alt breaker. I still had the problem. I returned to O'reilly's, they then told me my voltage regulator wasn't putting out enough volts.
I am still having a voltage problem. It seems to do ok as I run down the road but it doesn't put out sitting idle.
I consulted a local garage and they said they could by-pass the PCM and install a regulator on the fender/firewall.
Has anyone tried this? Will it work with out effecting other items inside the PCM?

bj-666

voltage cycling is normal in these trucks as the grid heaters kick on and off and cause a voltage drop when they turn on. once you reach i beleive 1250rpm the grid heater stay off. do a search for voltage fluctuations and you should see some more posts on the same subject. usually between 12v-14v fluctuations
good luck
Brandon

patdaly

Check out these threads, the first one has the best way to diagnose the Alt. I have seen.

https://www.dieseltruckresource.com/...ght=Alternator

https://www.dieseltruckresource.com/...ght=Alternator

https://www.dieseltruckresource.com/...d.php?t=148984

fryedaddy

Thanks for the in put. I'll repost/reply when I can get it resolved.